In some cases, a process of forming a film such as a silicon oxide (SiO) film or a silicon nitride (SiN) film containing a certain element, for example, silicon (Si), on a substrate may be performed during manufacture of semiconductor devices. A SiO film is widely used as an insulating film or an interlayer because of its high insulating property and low dielectric property. A SiN film is widely used as an insulating film, a mask film, a charge storing film or a stress control film because of its high insulating property, high corrosion resistance, low dielectric property and high film stress controllability. There have also been known techniques for forming a film such as a silicon carbonitride (SiCN) film, a silicon oxycarbonitride (SiOCN) film or a silicon oxycarbide (SiOC) film by adding carbon (C) to the SiO film or the SiN film. Such carbon addition allows for improvement to etching resistance of the film to hydrogen fluoride (HF). In addition, this carbon addition allows for a change in a dielectric constant and a refractive index of the film, and a carbon-added film can be used as an optical functional film or the like having a refractive index different from those of adjacent films.
In recent years, a need to lower a temperature at which a film is formed has increased with miniaturization and diversification of semiconductor devices. Studies on lowering of the film forming temperature have been actively made but conventional efforts have not been sufficiently successful. For example, it was difficult to form a silicon (Si) film using a monosilane (SiH4) gas or a disilane (Si2H6) gas at a range of low temperatures less than 500 degrees C.
In terms of wet etching resistance to HF, a SiN film and a SiCN film are superior to a SiO film and inferior to a Si film. In other words, the Si film is significantly different from the SiO film and the like in terms of processability (for example, wet etching resistance and so on), and is suitably used as a processing film used to process SiO film and the like (for example, a film for etching a mask used to etch an underlying SiO film and the like using HF). Thus, it is difficult to form a film which is significantly different in processability from the SiO film and the like at a range of low temperatures. Accordingly, if a film containing for example a Si, can be formed at a range of low temperatures, choices for processing film and the processing method may be expanded.